Microincision Cataract Surgery Group Research Articles

Posterior capsule opacification and capsular bag performance of a microincision intraocular lens

To assess the axial stability and posterior capsule opacification (PCO)-inhibiting efficacy of a microincision hydrophilic intraocular lens (IOL) (Idea 613 XC) and a standard hydrophobic open-loop acrylic IOL (Acrysof SA60AT). Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Clinical trial. Patients with bilateral cataract received a microincision cataract surgery (MICS) IOL in 1 eye and a small-incision cataract surgery (SICS) IOL in the contralateral eye. Follow-up examinations were performed immediately after surgery and postoperatively at 1 week and 3 and 24 months. Posterior capsule opacification was assessed using retroillumination photography. Anterior chamber depth (ACD) was measured using partial coherence laser interferometry, and IOL tilt and decentration were measured using a Purkinje meter. Seventy eyes (35 patients) were enrolled. The mean ACD at 3 months was 4.91 mm ± 0.26 (SD) in the MICS group and 4.60 ± 0.23 mm in the SICS group. The anterior IOL shift over the first 3 months was slightly smaller with the MICS IOL (81 μm) than with the SICS IOL (254 μm). The mean ACD was 0.377 ± 178 μm deeper with the MICS IOL (P<.01, paired t test). Two years postoperatively, the amount of regeneratory PCO was higher with the MICS IOL than with the SICS IOL (image analysis software score 2.6 versus 1.9; P=.005). Two years after surgery, the PCO rate was slightly higher with the MICS IOL. The 2 IOLs had similar performance in terms of axial stability, decentration, and tilt. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Factors influencing corneal biomechanical changes after microincision cataract surgery and standard coaxial phacoemulsification

To determine the factors affecting corneal biomechanics using biomechanical waveform analysis after microincision cataract surgery (MICS) and standard coaxial phacoemulsification with different incision sizes. Vissum-Instituto Oftalmologico de Alicante, Alicante, Spain. This prospective nonrandomized study comprised eyes with significant cataract that had MICS (sub-1.8 mm incision) or coaxial phacoemulsification (2.75 mm incision). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured by biomechanical waveform analysis (Ocular Response Analyzer) preoperatively, immediately postoperatively, and at 1 month. Results were analyzed and compared between groups. In the MICS group (n = 30), there was a significant increase in Goldmann-correlated intraocular pressure (IOP) and corneal-compensated IOP, although CH decreased in the immediate postoperative period (P<.05). At 1 month, all parameters in the MICS group returned to normal. The coaxial group (n = 30) had an increase in Goldmann-correlated IOP and corneal-compensated IOP, both of which were higher than normal at 1 month. Backward multiple regression analysis showed significant correlations between CH and preoperative Goldmann-correlated IOP and preoperative CRF (r(2) = 0.631, P<.05); between age, axial length (AL), and preoperative CRF (r(2) = 0.418, P<.05); and between the change in CH and AL, total incision length, and preoperative CH (r(2) = 0.429, P<.05). Cataract surgery with MICS and coaxial phacoemulsification significantly altered corneal biomechanics. Corneal hysteresis was inversely correlated with Goldmann-correlated IOP; CRF was inversely correlated with age and AL. The MICS technique provided more stable corneal biomechanical properties than standard coaxial phacoemulsification 1 month postoperatively.

Corneal incision quality: Microincision cataract surgery versus microcoaxial phacoemulsification

To use corneal optical coherence tomography (OCT) to evaluate the corneal incision quality in microincision cataract surgery (MICS) and microcoaxial phacoemulsification (microphaco). Vissum-Instituto Oftalmológico de Alicante, Alicante, Spain. Eyes with cataract grade II to IV were randomized into 2 groups for MICS or microphaco. Corneal incision quality was analyzed using corneal OCT on the first postoperative day, week, and month using a purpose-developed protocol and an objective model. Corneal OCT parameters were incision and corneal thickness, incision angle, epithelial and endothelial sealing, incision coaptation, and Descemet detachment. Visual, refractive, corneal topography, and aberrometric data were analyzed. There were no statistically significant between-group differences in corneal thickness and incision angle quality, geometrically assessed using corneal OCT. Corneal edema was less with MICS than with microphaco (44% versus 87%) (P=.002), as was corneal thickness in the 5.0 to 7.0 mm area (659.9 +/- 56.7 microm versus 697 +/- 80.6 microm) (P=.06), but only at 1 day. At 1 month, prolateness for an 8.0 mm area was maintained in the MICS group. Corneal root-mean-square astigmatism and residual were slightly better with MICS (0.6 +/- 0.4 microm versus 0.9 +/- 0.6 microm, P=.06; 0.6 +/- 0.2 microm versus 0.7 +/- 0.3 microm, P=.05). Other OCT outcome parameters did not differ significantly between groups. Microincision cataract surgery and microphaco provided similarly good incision quality and optically neutral incisions; the MICS incision respected corneal prolateness more, with less corneal edema in the short term and less induced corneal aberrations in the long term.

Postoperative corneal shape changes: Microincision versus small-incision coaxial cataract surgery

To compare changes in corneal topography and in regular and irregular astigmatism after coaxial clear corneal microincision cataract surgery (MICS) and after coaxial small-incision cataract surgery (SICS). Hayashi Eye Hospital, Fukuoka, Japan. Induced corneal astigmatism was determined using vector analysis. The averaged corneal shape changes and degree of irregular astigmatism were examined using videokeratography preoperatively as well as 2 days and 1, 2, 4, and 8 weeks postoperatively. One hundred twenty eyes of 60 patients scheduled for phacoemulsification were evaluated. Sixty eyes had MICS (2.00 mm), and the 60 contralateral eyes had SICS (2.65 mm). The mean induced corneal astigmatism was significantly less in the MICS group than in the SICS group (P <or= .0495) 1 week postoperatively and subsequently. The averaged difference map on videokeratography showed focal corneal flattening corresponding to the incision and coupled steepening around the flattened area 2 days postoperatively in both groups. The flattening and steepening gradually reduced to virtually the preoperative shape by 8 weeks; the changes were significantly less in the MICS group than in the SICS group. Of the irregular astigmatic components, higher-order irregularity was significantly less in the MICS group than in the SICS group up to 2 weeks postoperatively (P <or =.0470). Induced astigmatism, focal wound-related flattening of the peripheral cornea, and corneal surface irregularity were significantly less after coaxial MICS than after SICS.

Comparison Between Bimanual Microincisional Cataract Surgery and Conventional Coaxial Phacoemulsification

Purpose: To evaluate corneal endothelial cell changes after conventional coaxial phacoemulsification and bimanual microincision cataract surgery (MICS). Methods: Forty patients were divided into 2 groups, coaxial phacoemulsification (Group 1, n=20), and MICS (Group 2, n=20). To evaluate corneal endothelial cell changes after coaxial phacoemulsification and bimanual MICS, intraoperative phacoemulsification power and volume of intraoperative irrigation solution (balanced salt solution, BSS, Alcon, U.S.A) were measured. Central corneal thickness and endothelial cell count were also evaluated, preoperatively and at 1 week, and 2 months postoperatively. Results: Between the 2 groups, there was no statistically significant difference in intraoperative phacoemulsification power and volume of intraoperative irrigation solution (balanced salt solution, BSS, Alcon, U.S.A.) (p＞0.05). In addition, there was no statistically significant difference between the 2 groups in endothelial cell count and central corneal thickness (p＞0.05). Conclusions: When comparing bimanual MICS and conventional coaxial phacoemulsification, bimanual MICS appears to have similar endothelial cell changes. In conclusion, MICS has the same safety as compared to coaxial phacoemulsification.

Changes in corneal wavefront aberrations in microincision and small-incision cataract surgery

To study the effect of incision size on the optical quality of the anterior cornea by comparing the changes in corneal wavefront aberrations between microincision cataract surgery (MICS) and small-incision cataract surgery (SICS). Eye Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China. This prospective randomized clinical study included 36 eyes having MICS (1.5 mm) and 38 eyes having SICS (3.0 mm). Anterior corneal topography was measured preoperatively and 3 to 6 months postoperatively. The data were used to calculate anterior corneal Zernike aberrations (through the 6th order) for a 6.0 mm central area. In the MICS group, 2 corneal Zernike aberrations (trefoil and tetrafoil) changed significantly from preoperatively to postoperatively (both P<.0001). In the SICS group, in addition to trefoil and tetrafoil, oblique astigmatism (P<.0001), secondary oblique astigmatism (P= .001), and vertical tetrafoil (P= .001) changed significantly. The SICS group had greater changes than the MICS group in oblique astigmatism (P= .0001), oblique trefoil (P= .0035), and vertical tetrafoil (P= .0023). The changes in the SICS group were significantly greater than in the MICS group in the total root mean square (RMS) (P= .007) and higher-order RMS (P= .023) of corneal wavefront aberrations. Cataract surgery-related changes in corneal wavefront aberrations were dependent on incision size. The MICS technique had advantages over the SICS technique in minimizing the effect of the incision size on the optical quality of the cornea.

Comparative study of coaxial phacoemulsification and microincision cataract surgery: One-year follow-up

To evaluate the amount of ultrasound (US) used, best corrected visual acuity (BCVA), and corneal endothelial cell loss in bimanual microincision cataract surgery (MICS) and coaxial phacoemulsification. Department of Ophthalmology, Universidade Gama Filho, Rio de Janeiro, Brazil. A prospective randomized study included 30 patients (60 eyes) with bilateral cataract. All patients had coaxial phacoemulsification in 1 eye and MICS in the fellow eye. The US time and the effective US time were measured intraoperatively. The BCVA and central endothelial cell loss were evaluated in both groups over a 1-year follow-up. The results between the 2 groups were compared. The total US time was lower in the coaxial phacoemulsification group than in the MICS group; the means were 0.50 minutes +/- 0.33 (SD) and 0.82 +/- 0.39 minutes, respectively. The mean US power was similar between groups (mean 10.1% +/- 3.76% and 10.0% +/- 4.0%, respectively). The BCVA was similar between the groups from 24 hours to 1 year. The mean central corneal endothelial cell loss at 3 months was 4.66% +/- 6.10% in the coaxial phacoemulsification group and 4.45% +/- 5.06% in the MICS group and at 1 year, 6.00% +/- 6.72% and 8.82% +/- 7.39%, respectively. The only significant difference in the postoperative results between the 2 groups was central endothelial cell loss at the 1-year follow-up. The US time was longer in the MICS group than in the in the coaxial phacoemulsification group, but the mean US power was similar between groups. The BCVA was also similar between groups; however, the MICS group had more central endothelial cell loss at the 1-year follow-up.

Intraindividual comparison of surgical trauma after bimanual microincision and conventional small-incision coaxial phacoemulsification

To compare the surgical trauma after microincision phacoemulsification and small-incision coaxial phacoemulsification after implantation of conventional, foldable, hydrophobic acrylic intraocular lenses (IOLs). Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. A prospective investigator-masked case series comprised patients with bilateral cataract who had cataract surgery on the same day. Thirty-three patients (66 eyes) were randomized. Microincision cataract surgery (MICS) was performed through 2, 1.4 mm clear corneal incisions (CCIs) using bimanual sleeveless phacoemulsification (cool phaco) in 1 eye. Small-incision cataract surgery (SICS) was performed on the other eye through a 3.2 mm CCI. In all cases, an AcrySof SA60AT IOL was inserted, in the MICS group after the CCI was enlarged. Laser flare photometry, specular microscopy, corneal endothelial cell density, and pachymetry were evaluated preoperatively and postoperatively. Intraindividual comparison and statistical analyses were performed. There were no relevant clinical differences or perioperative complications in either group. There were no statistically significant differences between preoperative and postoperative anterior chamber flare or endothelial cell loss. On the first postoperative day, the MICS group had statistically significantly increased corneal swelling (P = .008). Postoperatively, the mean endothelial cell density loss was higher in the MICS group (6.2%) than in the SICS group (3.10%); however, the difference between groups was not significant (P = .08) Microincision cataract surgery was a safe and reproducible technique. The postoperative results in the MICS group were comparable to those in the SICS group.

Evaluation of Early Corneal Endothelial Cell Loss in Bimanual Microincision Cataract Surgery (MICS) in Comparison with Standard Phacoemulsification

To analyze early corneal endothelial cell loss due to microincision cataract surgery (MICS) in comparison with standard phacoemulsification through the temporal clear corneal incision. The examined group consisted of a nonrandomized, consecutive prospective series of 20 eyes of 20 patients who underwent uneventful microincision cataract surgery. Twenty eyes of 20 patients who underwent standard phacoemulsification with foldable intraocular lens (IOL) implantation served as a reference group. Patients with corneal disorders, contact lens wear, previous intraocular surgery, and a history of ocular trauma were excluded from the study. Patients were examined preoperatively and 10 days postoperatively. The following items were evaluated in this study: corneal endothelial cell density, intraoperative phaco power, effective phaco time, as well as pre- and postoperative visual acuity. Corneal endothelial cell counts were done in the central part of the cornea using a non-contact Topcon SP 2000P specular microscope before and 10 days after the surgery. The measurements were performed in a semiautomated, masked manner. Statistical analysis was done using nonparametric tests (Wilcoxon signed-ranks test and Mann-Whitney U test). All patients in the study underwent uneventful surgery. Best-corrected visual acuity (BCVA) examined 10 days postoperatively in the MICS group was 0.94+/-0.094, whereas in the standard phacoemulsification group it was 0.90+/-0.094. There was no significant difference between BCVA in the two groups (Mann Whitney U two-tailed test: p>0.05). In both groups there was a significant decrease in postoperative endothelial cell densities (ECDs) when compared to preoperative values. Mean postoperative ECDs were 2235+/-418 cells/mm2 in the MICS group and 2079+/-399 cells/mm2 in the standard phacoemulsification group; the difference was not statistically significant (Mann-Whitney U test: p>0.05). Patients in the MICS group lost an average of 9.5% of cells, whereas patients after standard phacoemulsification lost about 7.6% of cells. This difference was statistically insignificant. Microincision cataract surgery induced corneal endothelial cell loss similar to a standard phacoemulsification and allowed excellent visual results in this series of patients. These results support the use of MICS technique for cataract surgery.

Corneal endothelial damage after cataract surgery: Microincision versus standard technique

To compare corneal endothelial changes after phacoemulsification performed with a standard technique versus a bimanual microincision cataract surgery (MICS) technique. University ophthalmology department. Eighty patients scheduled for routine cataract surgery were randomized into 2 groups; 40 eyes had standard stop-and-chop phacoemulsification (standard group) and 40 eyes had stop-and-chop phacoemulsification with microincision surgery (MICS group). Central corneal endothelial cell counts, coefficient of variation in cell size, hexagonality, and pachymetry were assessed preoperatively and 1 and 3 months postoperatively. The mean preoperative cell count in the entire sample was 2245 cells/mm2 +/- 37 (SE). The mean decreased by 102 cells at 1 month (95% confidence interval [CI], -133 to -71; P < .001) and by 144 cells at 3 months (95% CI, -187 to -102; P < .001). The difference between the standard group and the MICS group was 25 cells at baseline (95% CI, -169 to 120 cells; P = .739), 19 cells at 1 month (95% CI, -163 to 126; P = .799), and 19 cells at 3 months (95% CI, -164 to 125; P = .793). There were no changes in the coefficient of variation or morphology in the overall sample, and the pattern of change did not differ between the 2 groups. Corneal thickness increased by 10.2 microm in the overall sample (95% CI, +4.5 to +16.0; P < .001) and approached baseline values by 3 months with an increase of 3.4 microm (95% CI, -4.1 to 10.8; P = .372). There was no difference in corneal thickness between the groups. No significant differences in corneal endothelial cell loss or endothelial morphology were found between MICS and standard incision techniques.

Outcomes of Microincision Cataract Surgery versus Coaxial Phacoemulsification

To compare outcomes of microincision cataract surgery (MICS) with coaxial phacoemulsification. Prospective randomized consecutive case series. One hundred eyes of 50 patients with nuclear or corticonuclear cataract (grades 2+ to 4) with Lens Opacities Classification System III. One hundred eyes (50 patients) were randomly operated through clear corneal incisions using 2 techniques: coaxial phacoemulsification (50 eyes) and microincision cataract surgery (50 eyes). Mean phacoemulsification time, total phacoemulsification percent, effective phacoemulsification time (EPT) (calculated by multiplying total phacoemulsification time in seconds by the average power percent used), intraoperative total balanced salt solution (BSS) volume, visual outcome, vectorial astigmatic changes, corneal thickness, endothelial cell count, and anterior chamber flare and cells preoperatively and at 1 day, 1 month, and 3 months. Statistically significant differences were found between MICS and coaxial phacoemulsification regarding mean incision size, mean total phacoemulsification percent, and EPT. There were no significant differences between the techniques regarding the mean percent of endothelial cell loss, anterior chamber cell count and flare, mean phacoemulsification time, pachymetric measures or total BSS volume utilized, or visual outcome. The vectorial astigmatic changes in the MICS group showed a change of < or =0.25 diopters (D) in 35% of the eyes, 0.25 to 0.5 D in 50% of the eyes, and 0.5 to 1.0 D in 15% of the eyes. These changes were induced by the surgery. Vectorial astigmatic changes of >1 D were not observed. In the coaxial phacoemulsification group, vectorial astigmatic changes of <0.25 D were not observed either. Changes of 0.25 to 0.5 D were seen in 20% of the eyes, and changes of 0.5 to 1.0 D were seen in 30%. Fifty percent of the eyes showed changes of >1.0 D. Mean vectorial astigmatic changes were 0.36+/-0.23 D in the MICS group and 1.2+/-0.74 D in the coaxial phacoemulsification group (P<0.001). Microincision cataract surgery significantly lowered mean phacoemulsification time, mean total phacoemulsification percent, mean EPT, and surgically induced astigmatism when compared with coaxial phacoemulsification.